1. Field of the Invention
This invention relates generally to mechanic's tools and more particularly to tools useful in facilitating the removal of thread locked or "stuck" nuts or bolts where it is necessary to bring a large torque to bear about the axis of the stuck element.
2. Description of the Prior Art
Torque, sometimes denonted the moment of a force about an axis, is the effectiveness of that force in producing rotation about that axis. Torque is measured by the product of the incident force with the perpendicular distance from the axis to the line of action of that force. Of course, the inventive device described herein does not vary the incident force, however, by adjusting the length of the device, the perpendicular distance from the axis is varied thus modifying the torque, the moment of the force about the axis. Thus, it is a fact of common experience that the longer the lever arm of the breaker-bar tool at our disposal, the easier it is to break a thread lock between a nut and a bolt, for instance.
While presently available extensible handles for tool headpieces can also vary applied torque by changing the lever arm, i.e., the perpendicular distance from the axis of desired rotation to the line of action of the applied force, some disadvantages of these prior art devices include limited numbers of positions to which adjustment can be effected in order to vary the lever arm. In one particular case, the total number of positions available is only two, being one position in which an inner member is completely retracted, the shorter position, and the other position in which the inner member is completely extended, the longer position. The tool in question is complicated to fabricate, having a spring-loaded inner member and machined surfaces and slots that increase production expense. In another case, an inner member is restricted to a hexagonal cross sectional shape requiring slots to be machined on one flat face thereof and having an adjustment locking mechanism comprising multiple small parts contributing to a higher fabrication cost and likelihood of malfunction. An additional particularly interesting prior art device includes ellipsoidal detents machined into an inner member for the acceptance of a metal ball utilized to maintain the integrity of adjustment. The metal ball so utilized is held captive by means of a cylindrical sleeve of complicated inner machining, being itself spring-loaded and having inwardly projecting rims, a ball chamber and a spring chamber. While the tool presents an interesting mechanical design, it is complicated and expensive and may be prone to disorder when compared to the device contemplated by the present invention. Yet another torque-varying device provides for but two positions while presenting a complicated machining problem with its attendant expensive fabrication cost and proclivity for breakdown. One of the most interesting of the devices encountered in applicant's novelty search is the tool described by Hoke et al in U.S. Pat. No. 4,047,821 for BREAK RESISTANT TELESCOPING TOOL. The tool is described as " . . . insulative, multi-section, break-resistant telescoping tool especially adapted for work around energized electrical lines . . . . " One of the main advantages of the tool described resides in its having " . . . imperforate bases which preclude air flow centrally . . . to thereby prevent the quick escape of air . . . during nesting retraction of the tool which serves to cushion such retractive movement and prevent inadvertent breakage of the sections." It is thus the shock-absorptive effects of the motions during retraction of the tool sections that appears to be of prime interest in this particular device.
These prior art devices among other disadvantages, have been unreliable and unpredictable in operation as a result of their complicated designs, and have been expensive and difficult to manufacture. At least one of the devices has met only a special need as presented by a specific problem and thus has served only a narrow purpose. Some of these prior art devices have been described in the following listed patents that were brought to the attention of applicant's attorney through a novelty search conducted in the U.S. Patent and Trademark Office:
______________________________________ U.S. Pat. No. Patentee Shortened Title ______________________________________ 4,070,932 Jeannotte Extensible Handle 4,047,821 Hoke et al Break Resistant 3,306,639 Lyon Extensible Torque Rod 2,963,930 Clothier Extensible Torque Bar 2,282,148 Mandl Tool Handle 2,263,508 Lee Extensible Handle Assembly ______________________________________
It would thus be a great advantage to the art to provide an adjustable, torque-multiplier breaker-bar that is economical and uncomplicated to fabricate.
Another great advantage would be the provision of an adjustable, torque-multiplier breaker-bar that is easy to adjust.
A further desirable advantage would be realized in a tool of the type contemplated by the present invention by the provision of multiple adjustments while maintaining the advantage of ease of adjustment mentioned above.
A still further advantage would be found in the maintenance of the integrity of length settings without the incorporation of complicated mechanisms.
Yet another important advantage would be defined in a tool of the type contemplated by the present invention if the tool could be made simple and easy to use while retaining the advantages previously mentioned.